Approximate Entropy Detection Spectrum Sensing in Cognitive Radio

As a new type of radio system, Cognitive Radio (CR) is able to sense the spectrum condition, and according to the result of spectrum sensing to determine the free available frequency band for transmission, in which, the key problem is how to determine whether the spectrum band is idle. The letter presents a new spectrum sensing approach based approximate entropy (ApEn) to determine what spectrum is occupied in frequency. Simulation and analytical results show that the value of ApEn always decreases as the SNR increases, and the detector based ApEn have ability to effectively complete the spectrum sensing.